Subject dictionaries and encyclopedias can give you definitions and descriptions of terms, theories and concepts. They are a great starting point for a new topic when you are not familiar with the specific terminology.
Note: some titles are available as print books and some are available electronically
APA Concise Dictionary of Psychology by 
APA Dictionary of Lifespan Developmental Psychology by 
APA Dictionary of Statistics and Research Methods by 
Dictionary of Forensic Psychology by 
Dictionary of Multicultural Psychology: Issues, terms and concepts by 
The SAGE Glossary of the Social and Behavioral Sciences by 
Thesaurus of Psychological Index Terms by 
The Corsini Encyclopedia of Psychology by 
Encyclopedia of Psychology by 
Encyclopedia of Psychology and Religion by 
